The invention generally relates to bone joint prostheses, and more particularly is concerned with an elbow prosthesis which allows a limited amount of medial-lateral motion in addition to flexion and extension motion. In addition, it presents a means of affixing a polyethylene bearing member to a metal ulnar component.
Elbow prostheses are generally totally restrained (hinged), semirestrained or unrestrained (hingeless).
In the past, many two component prostheses employed a metal on metal articulating surface. This results in abrasion of the contacting parts and release of metallic particles which are dispersed to the tissue surrounding the implant. This is an undesirable result. It has been found that a metal on non-metal articulating surface is much more desirable and provides better wear characteristics. Often one component is made of metal and one is made of a non-metal material such as polyethylene. In recent years, many prostheses utilize a metal component with a metal retained or reinforced polyethylene bearing surface. This allows a metal on polyethylene bearing surface, but still allows the strong support of the metal retainer.
U.S. Pat. No. 3,816,854 to Schlein discloses a hinged prosthesis for the elbow join including a humeral component terminating in a partial cylinder. A polyethylene bearing member is fitted within the partial cylinder and is provided with a slot. The ulnar component includes a U-shaped member having arms for supporting a pin. The pin engages the slot in the bearing member to provide rotation between the components.
U.S. Pat. No. 3,868,730 to Kaufer, et al. and U.S. Pat. No. 4,112,522 to Dadurian, et al. discloses other examples of joint prostheses which employ inserts between rotating member.